Reflectance Of Films Research Articles

Effects of NIR Reflective Film as a High Tunnel-Covering Material on Fruit Cracking and Biomass Production of Tomatoes

Tomatoes require higher irradiance, although the incidence of physiological disorders in fruit increases at high temperatures. Near-infrared (800–2500 nm) (NIR) reflective materials are effective tools to suppress rising air temperatures in greenhouses. We examined the physiological and morphological changes in tomato growth and fruit quality when grown in a high tunnel covered with NIR reflective film (NR) and in another covered with polyolefin film (PO; control). There was no relationship between the fruit cracking rate and mean daytime temperature under NR. The fruit temperature at the same truss was lower and the increase in air temperature was slow under NR. Fruit dry matter (DM) content under NR was also significantly decreased. These findings suggest that the reduction in fruit cracking under NR results from a decrease in fruit DM content as a consequence of lower fruit temperature and a decrease in total DM (TDM). Total fruit yield did not differ, whereas TDM was significantly decreased under NR. This was considered to result from a lower transmitted photosynthetic photon flux density (400–700 nm) (PPFD) and LAI, and lower photosynthetic capacity in single leaves because of a decrease in both total nitrogen and chlorophyll content. We conclude that NR film reduces fruit cracking in exchange for a slight reduction in TDM.

Research on the law of reflection coefficient of reflective film of traffic sign based on Angle

In this paper, a large number of digital printing reflective film retroreflectivity measurement. Based on the multi-angle test of the reflective film of the mainstream manufacturers in the market, the reverse reflection coefficient of the digital printing reflective film was obtained. Through the curve fitting of the measured values of the backreflection coefficient under different measuring angles by using the scatter plot, the variation law of the luminosity of the digital printing reflective film with incident Angle and observation Angle was obtained. The variation law of backreflection coefficient explored in this paper has certain significance to the application guidance of digital printing reflective film for traffic signs.

Influence of retroreflective films on the behaviour of elastic guided waves measured with laser Doppler vibrometry

Retroreflective films are often used to enhance ultrasonic motion sensing with laser Doppler vibrometry by increasing surface reflectivity of metallic and polymer structures. This study reveals that such a surface modification leads to undesirable effects, which manifest themselves in notable changes of observed structural elastodynamic properties. The provided analysis shows systematic changes in dispersion curves of fundamental and high order guided waves propagating in laminates and significant amplification of their attenuation. Therefore, to avoid mistakes and additional errors when interpreting results of such measurements, e.g., in application to ultrasonic material characterization, the presence of reflective films should be considered and properly quantified.

Development of the aluminum substrate reflective film in the off-axis three-mirror optical system

Development of the aluminum substrate reflective film in the off-axis three-mirror optical system

Divergence Performance of Reflective Film Enhanced by Microlenses Combined with Non-standard Pyramid Structure

Divergence Performance of Reflective Film Enhanced by Microlenses Combined with Non-standard Pyramid Structure

Tunable thermal management based on solar heating and radiative cooling

Solar heating (SH) and radiative cooling (RC) have been regarded as promising clean techniques for thermal energy harvesting and temperature control. However, SH and RC are only a single function of heat collection and dissipation, which means the static device of SH and RC cannot meet the dynamic heat requirement of real-world applications, especially in the daytime. Here, a strategy of dynamic integration of SH and RC is proposed for tunable thermal management. A device (i.e., SH/RC device) that includes a silica cavity, ultrapure single-walled carbon nanotubes (SWCNTs) aqueous dispersion, solar reflective film, and deionized water is designed and fabricated. The outdoor experimental results show that the SH/RC device with SWCNTs media can effectively achieve heat collection with a maximum temperature of 78.9°C, while the SH/RC device with deionized water can achieve heat dissipation. Besides, the temperature modulation ability of the SH/RC device is tested to be 26.3°C and can be theoretically improved to be 60.3°C by improving the solar absorptivity (i.e., 0.9 for SH mode and 0.1 for RC mode) regulation ability of the device and improving its thermal emissivity (i.e., 0.9). Furthermore, annual analysis indicates that the cumulative time in which the SH/RC device temperature is in a comfortable region (i.e., 20°C-26°C) for humans is 60.9% and 30.3% higher than that of the device with individual SH and RC mode. In summary, this work provides alternative thinking for tunable thermal management based on the dynamic utilization of the hot sun and cold universe. • Dynamically integration of solar heating (SH) and radiative cooling (RC) is proposed. • Tunable thermal management can be achieved by SH/RC device. • Temperature modulation ability of SH/RC device is tested to be 26.3 °C and can be improved to 60.3 °C. • Cumulative time that the device is within a comfortable region is enhanced by 30.3%–60.9%.

Integration of Phase Change Material in the Design of Solar Concentrator-Based Water Heating System.

Indonesia has been blessed with excellent solar heat distribution, which can be used as renewable energy to heat water. Various technologies have been developed to utilize these inexhaustible thermodynamic resources, in the form of photons arrays, converted into concentrated heat for daily use, i.e., solar water heater. This renewable-based water heating system can provide significant energy efficiency, benefit the environment, and reduce energy use costs. This experimental study attempts to harvest the energy from the sun using a cylindrical through collector (CTC) type solar concentrator. The CTC was made of the solar reflective film (SRF) affixed to concentrator collector surfaces which was then mounted on an adjustable angle frame of the concentrator collector support. The heat generated from the concentrator was stored in water, and phase change material is embedded in the system to retain the heat longer. The research was carried out in Langsa City, Aceh, Indonesia. The results showed that water heaters using CTC systems could produce 16 L of hot water retained at 40–60 °C for four hours. With the addition of beeswax, the water temperature of the same capacity can be maintained at 40–60 °C for around 5 h. This technology demonstrated an excellent result that produces as much as 60 L of water per day, increasing solar thermal energy efficiency. This technology presented a great potential for replication or even for further development on an industrial scale.

Development of Wavelength-Selective Transmission and Reflection Film for 2D-Backlight with Blue Mini-LEDs

Development of Wavelength-Selective Transmission and Reflection Film for 2D-Backlight with Blue Mini-LEDs

P210 - Non-uniformity error (noise) reduction of reflective type radiochromic films

P210 - Non-uniformity error (noise) reduction of reflective type radiochromic films

Ultra-low stress high reflective film by dual-ion-beam sputtering deposition

The correlation between the process parameters of auxiliary ion source and the SiO2 film stress was systematically studied using dual-ion-sputtering deposition. Spectrophotometer and ellipsometer were used to measure the SiO2 film’s transmittance spectrum and reflection ellipsometry. The refractive index and thickness of SiO2 film were obtained by total spectrum inversion calculation. The laser interferometer measures the substrate surface shape to obtain film stress. The experimental result shows that film stress is related to sputtering energy during deposition, high-energy oxygen ion assisted deposition can significantly reduce it and the assisted ion beam voltage plays an important role in controlling it by data normalization analysis. Ultra-low stress high reflective film was prepared by dual-ion-beam sputtering deposition, where stress was 70% lower than traditional film. At the same time, this film can ensure sufficiently high optical quality to keep it reliable and stable in high-precision laser systems.

Experimental investigation on ventilated window with reflective film and development of correlations

The present experimental study investigates ventilated windows with and without reflective film for hot climate applications. Experimental data on ventilated windows with reflective film for hot climate applications are scarce in the literature. Hence, the objectives of the study includes the provision of experimental results on ventilated windows with and without solar reflective films which is lacking in the literature, strengthening the validation of the developed numerical code, and finally development of validated correlations for the ventilated windows with and without reflective solar film. The experimental rig was built and instrumented for outdoor tests of windows of different configurations. Experiments were conducted on three window configurations which were assessed numerically using the numerical code. The configurations included a traditional single glass window, ventilated window with reflective film and ventilated window without reflective film. The numerical predictions were compared with the experimental results showing good agreement. The results indicated that the temperature decrement increased with the increase of the gap between the glass sheets and that a spacing more than about 0.03 m has marginal effect. The experiments confirmed that the ventilated window with film is more efficient and that it can reduce the energy gain by almost 57% and hence can be recommended for hot climate. The developed correlations showed maximum deviation for the case of the window with film of about 13% and about 7% for the case without film.

Preparation of a highly-reflective gold thin film by a sputtering technique using ionic coating system

Metallic mirror coatings with high reflectivity using Au thin films deposited onto a Borosilicate BK7 glass substrates by a sputtering technique using ionic coating system (KIC-1A) were investigated. In order to facilitate the process of calculating the relationship between deposition duration and thin film thickness to reach to a certain thickness, so we have described and calculated the relationship between deposition duration and thin film thickness by theoretical analysis and then simulated by polynomial function. This study showed the relationship between the reflection and thin film thickness, where the highest value of the reflective coatings of 90.5% was obtained at thin film thickness of 153 nm.

Improvement of color-rendering characteristics of white light emitting diodes by using red quantum dot films

Red quantum dot (QD) films were applied to a conventional white light-emitting-diodes (LEDs) module consisting of 72 LEDs for improving color-rendering properties. Total three QD films with different QD concentrations, two diffuser plates, and six optical configurations were combined and investigated to find an optimized optical structure. QD films formed a red peak near 630 nm in the spectrum which significantly increased the overall color rendering index (CRI). The lateral optical cavity formed by a vertical QD wall and the vertical cavity formed by the diffuser plate and the reflection film in the lighting module played an important role in the improvement of the color-rendering properties. Especially, the adoption of the lateral optical cavity formed by the QD wall was an effective way to improve both efficiency and color rendering properties of the LED lighting. The present result suggests a new possibility of designing high-CRI LED light sources whose color properties can be tuned easily by simply applying and relocating QD components in conventional LED lightings.

Luminous efficacy enhancement for LED lamps using highly reflective quantum dot-based photoluminescent films.

In this study, a strongly reflective and photoluminescent (PL) poly(lactic-co-glycolic acid) quantum dot (QD) hybrid nanofiber (PQHN) structure is introduced to enhance the luminous efficacy of QD-phosphor hybrid white light-emitting diodes (QD-WLEDs). As the thickness of PQHN film increases, the PL is found to continuously increase, exhibiting a maximum peak intensity at 120 μm, which is 1.92 times that at 12 μm, and showing the highest diffuse reflectance of 94.4% at 640 nm. Consequently, while using the QD-WLEDs, the PQHN structure achieves a 53.8% improvement in luminous flux compared with the traditional structure under a similar correlated color temperature (CCT) of 3,540 K, achieving a high luminous efficacy of 202.11lmW-1 for QD-WLEDs. In addition, the maximum deviation of the CCT is only 11 K when the current is changed from 50 to 950 mA, demonstrating good stability. Therefore, the PQHN films have great potential in lighting systems as a hybrid functional film including light conversion and reflectance.

Optical design of a tension cable-membrane concentrator

This paper proposes a Tension Cable-Membrane Concentrator with an ultra-lightweight, practical and low cost alternative construction which is used in the optical-electrical conversion system. The relationship between the varied count triangular facets of the membrane surface and the focal spot radius are studied. Based on Monte Carol ray-tracing method, the optical performances of the concentrator, such as the concentrate ratio, flux distributions and focal spot radiuses etc., are analyzed in different geometry design parameters. Further, a 15 m aperture Tension Cable-Membrane Concentrator is designed, and the form-finding design is studied and verified by ANSYS®. The optical performance comparisons with the original and pre-stressed shape of the reflective film are discussed. Simulation results exhibit that the surface density of the proposed Tension Cable-Membrane Concentrator is only 5% of that of traditional rigid concentrator. It takes on the ultra-lightweight and low-cost that excite designers. The optical performance comparisons show that the peak flux distribution after form-finding over a 0.25 m receiver approximately deliver up to 800 kW/m2 corresponding to the peak concentrate ratio exceeds 1000 suns which are even better than the traditional steel design and completely satisfy design requirements.

Butterflies see wing colours change as mother-of-pearls flutter by

For centuries, our predecessors experimented with exotic pigments to create opulent ceramics and illuminated manuscripts. It was only in the 18th century that we discovered Mother Nature's alternative colour palette, produced by light reflecting from microscopic layers in feathers, skin and insect shells in a similar way to the shimmering rainbow hues of soap bubbles and oil films. ‘Earlier in my career, I was devoted to insect vision, but I was also constantly intrigued by the often brilliant colours of butterflies’, says Doekele Stavenga, from the University of Groningen, The Netherlands, who became increasingly fascinated by the intriguing physics of these so-called ‘structural colours’. After decades of investigating the startling shades of butterflies from all over the globe, he most recently turned his attention to the shimmering common mother-of-pearl butterfly (Protogoniomorpha parhassus) from Africa in the hope of discovering how they produce their opalescent glow.As butterfly wings are coated in scales, Stavenga suspected that thin layers in these structures were the cause of the mother-of-pearl butterfly's delicate iridescent pink hue. However, to be sure, he first had to shine light through the fragile wings. ‘The structural coloration of the wings was immediately and strikingly clear when comparing light reflecting from the wing with light that passed through it’, says Stavenga, who saw the rosy shade vanish when the wing was illuminated from beneath. And when Bodo Wilts, a colleague from the University of Fribourg, Switzerland, scrutinised the scales in fine detail using an electron microscope, they could clearly see box-like structures in the scales that would scatter light to produce the butterfly's pearlescence. Next, Stavenga focused a spot of bright white light on a wing from above, producing a fuchsia-coloured beam as the structures in the scales reflected only red and blue wavelengths, confirming that the delicate colour is produced by reflecting structures in the scales and not a rose-toned pigment in the wing.However, Stavenga also knew that the tones produced by these light-reflecting colour-generating structures depend on the position of a viewer relative to the structure, potentially altering the colour of an object as it moves. Could the wings of mother-of-pearl butterflies flash different tones as the animals flutter by? This time, Stavenga shone white light at angles ranging from directly above the wing to almost horizontally to one side (an oblique angle of 70 deg), recording the wavelengths that were reflected by the scales to find out whether the shade varied from different angles. Impressively, the wing's hue switched from pink to yellow as the light shifted from above to one side. And, when he calculated how the colours would change in the eyes of a butterfly – which see UV tones but not the red hues that we can see – the wings became a brighter shade of yellow and the light was more strongly polarized, making the wings stand out for creatures such as butterflies that see polarization.The mother-of-pearl butterfly's wings are perfectly tuned to generate flashes of colour as they flit past, and Stavenga suggests that the fluttering insect's flickering light show could help them to stand out from the crowd. ‘Only in the last decade has the importance of butterfly wing scales acting as thin film reflectors like soap bubbles become well recognized, and the mother-of-pearl butterfly is certainly the brightest, exemplary case’, he says.

Study on HfO 2 /SiO 2 high reflective film damage induced by 248nm UV excimer laser

The deep ultraviolet optical thin films play an important role in excimer lasers, deep ultraviolet lithography machine and other laser systems. In this paper, the experiment on damage in HfO2/ SiO2 high reflective film irradiated by 248nm ultraviolet excimer laser was carried out. And the high reflection film is coated with a layer of SiO2 as a protective film. The damage morphology and depth of the samples were observed and analyzed by means of DIC microscope and surface profiler system. In this experiment, the laser-induced damage threshold of HfO2/ SiO2 high reflective film coated with SiO2 protective film was calculated by zero damage probability. Based on the surface characteristics of the damage points, we established the model to analyze the damage mechanism of the high reflectance film by using Finite Element Method(FEM). The experimental results show that the damage threshold of 248nm excimer laser to the highly reflective film is 3.086J/cm2. When the incident laser energy is 3.33J/cm2, stress damage appears on the surface of the highly reflective film. With the increase of laser energy, the high reflective film will appear melting damage and corrugated damage.

Silver films on aluminum alloy 6061 modified by ion bombardment improves surface reflectivity

Aluminum alloy substrates are widely used in military and civilian fields. However, the surface roughness of aluminum alloy materials is relatively large high due to the existence of tool marks after processing, which affects the optical performance. Reflectivity can be improved by Covering the surface of aluminum alloy 6061 with silver films can improve reflectivity. In order to develop long-term stable highly reflective silver films, a protective dielectric layer was first designed, and then deposited by electron beam evaporation. Covering a few more dielectric layers on the silver film, the reflectivity was further improved. Ar + bombarding the surface of the silver film can smooth the surface grains, and use this to evaluate its influence on the reflectivity performance. The reflectivity of the silver film is not only related relates to the evaporation rate and Ar + bombardment, but also related relates to tool marks and surface morphology. Ar + bombardment can significantly increase the reflectance of silver films in the wavelength range of 400–1000 nm at an evaporation rate of 15 Å/s. On the surface of AA6061 substrate, the double sutured layer and ion bombardment on the surface of silver film combined with dielectric interface can isolate the effect of knife marks, which can lead to the improvement of reflectivity.

The wing scales of the mother-of-pearl butterfly, Protogoniomorpha parhassus, are thin film reflectors causing strong iridescence and polarization.

ABSTRACTThe dorsal wings of the mother-of-pearl butterfly, Protogoniomorpha parhassus, display an angle-dependent pink, structural color. This effect is created by light interference in the lower lamina of the wing scales, which acts as an optical thin film. The scales feature extremely large windows that enhance the scale reflectance, because the upper lamina of ridges and cross-ribs is very sparse. Characteristic for thin film reflectors, the spectral shape of the reflected light strongly depends on the angle of light incidence, shifting from pink to yellow when changing the angles of illumination and observation from normal to skew, and also the degree of polarization strongly varies. The simultaneous spectral and polarization changes serve a possibly widespread, highly effective system among butterflies for intraspecific communication during flight.

Approach to Performance Rating of Retroreflective Textile Material Considering Production Technology and Reflector Size

Abstract The study investigates retroreflective fabrics’ efficiency from the point of view of the interaction of their visibility, thermo-physiological comfort properties, and durability (represented by physical-mechanical performance). The effect of the combination of two production technologies (reflective transfer films and screen printing method) and two reflector covering sizes (25% and 85%) was examined. Technique for order of preference by similarity to ideal solution (TOPSIS) method was used to determine the best solution considering the abovementioned tested categories of properties. Retroreflective performance was in congruence with the used design coverage factor of the tested pattern. It was found that retroreflection of the tested pattern produced using screen printing technology was significantly lower than retroreflection of an identical pattern made by a transfer film. On the contrary, in terms of thermo-physiological comfort and physical-mechanical performance of the tested samples, screen printing technology shows significantly better results in almost all tested properties, especially in water vapor permeability, moisture management, and physical-mechanical performance. The solution for the abovementioned contradictory results can be achieved by using a combination of the advantages associated with each of these technology methods. Screen printing can be applied to specific regions of clothing that are exposed to extreme loading or sweating, and the transfer of film elements ensures high visibility with respect to the standards and biomotion principles that are deployed as prevalent benchmarks in the industry.